| GMC V8 engine | |
| Manufacturer: | General Motors |
| Production: | 1966–1972 |
| Configuration: | 60° V8 |
| Valvetrain: | OHV 2 valves × cyl. |
| Fueltype: | Gasoline, Diesel |
| Fuelsystem: | Carburetor |
| Coolingsystem: | Water-cooled |
| Block: | Cast iron |
| Head: | Cast iron |
| Displacement: | 6371NaN1 |
| Bore: | 5.125inches |
| Stroke: | 3.861NaN1 |
| Power: | 1921NaN1 |
| Torque: | 3711NaN1 (net) |
GMC has both shared engine designs and architectures with other General Motors divisions as well as having a history of developing and using its own unique engines and powertrains such as its line of straight-6 and V8 engines.
GMC's own V8 was the 6371NaN1 unit, which was essentially a 478 V6 with two cylinders added. It shared the NaNinches bore and stroke and used a single camshaft. It was manufactured in gasoline and diesel versions, and was the largest-displacement production gasoline V8 ever made for highway trucks. The GMC 637 V8 was produced from 1965 to 1973.[1]
Prior to developing its own engines, smaller GMC trucks used the Pontiac V8 engine. They used the Pontiac 2871NaN1 engine for 1955 and 3161NaN1 engine in 1956, but advertised the engines as the "GMC 288" and "GMC 316". They used Pontiac's 3471NaN1 in 1957. For 1958, GMC reduced the bore of Pontiac's 3701NaN1 to 3.875inches, resulting in a displacement of 3361NaN1. (In Canada, however, GMC used the Chevrolet small-block engine rather than the Pontiac.) For 1959, as the Pontiac engine's stroke was lengthened to 3.751NaN1, a further bore reduction to 3.781NaN1 was done to keep the displacement at 336.7cuin.
Starting in 1955, for the larger trucks, the Oldsmobile Rocket V8 was available. In 1955 and 1956, it was 324cuin. Power listed for 1956 was 210 hp @ 4200 rpm; torque was 305 lb-ft @ 2400 rpm. For the 1957 through 1959 model years, it was upped in bore and stroke and called the 370. Power was listed as 232 hp @ 4200 rpm and torque as 355 lb-ft @ 2600 rpm.[2]
From 1955 through 2003, GMC shared Chevrolet's small-block V8. This came in 265, 283, 305, 327, 350, and 400 cu in (4.3, 4.6, 5.0, 5.3, 5.7, and 6.6 L) sizes.
GMC also shared Chevrolet's big-block V8 from 1968 through 2009. The company used the 366, 396, 402, 427, 454, and 496 (6.0, 6.5, 6.6, 7.0, 7.4, and 8.1 L) versions.
Beginning in 1999, GMC began offering GM's LS-based "small-block" V8 engine in various models. Through the years, engines have been offered in 4.8, 5.3, 6.0, 6.2, and 6.6-liter displacements.[3]
Beginning in 2001, GMC offered the same turbocharged diesel Duramax V8 engines as were available in similar Chevrolet trucks. The engine family was co-developed by GM Powertrain and Isuzu, and has gone through numerous iterations through the years. Duramax engines are paired with a heavy-duty automatic transmission from GM's Allison division. [4]